Here's are the charts. For the charts of specific beard styles, the Y axis shows the level of frequency out of the total of all bearded men. The bottom chart summing all styles shows the level of frequency out of all men in the sample:

According to the paper, historical events don't seem to have been the cause of rising beardlessness. The safety razor started its rise to dominance around 1905, but the trend towards being clean shaven had already been going on for years.

It's about shifting style preferences. The data comes from a relatively small subset of elite, British men, but its still a fascinating shift.

If male celebrities, Lloyd Blankfein, or residents of Brooklyn are any indication, facial hair is in the midst of a renaissance, so it would be fascinating to see these charts updated somehow. The paper estimates the "trough to trough" period to be around 100 years across different styles, so we may be due for a resurgence.